Effects of different rapeseed varieties on egg production performance, egg quality, hormone levels, follicle...

This study was to evaluate the effects of rapeseed (Brassica napus L.) from China with different content of glucosinolate (Gls) and erucic acid (EA) on laying hens. A total of 600 laying hens at 33 wk of age were randomly divided into 5 treatments containing a control diet and 4 diets with 11.5% rapeseed. The 11.5% rapeseed diets varied in Gls and EA levels: 1) Deyou no. 6 (DY6) with Gls at 22.67 μmol/g and EA at 0.7%, 2) Mianbangyou no. 1 (MB1) with Gls at 43.23 μmol/g and EA at 3.5%, 3) Deyou no. 5 (DY5) with Gls at 74.66 μmol/g and EA at 16.20%, 4) Xiheyou no. 3 (XH3) with Gls at 132.83 μmol/g and EA at 44.60%. Each group had eight replicates and each replicate had 15 hens. The trial lasted for 12 wk with 4 wk withdrawal. From 1 to 8 wk of the trial, 11.5% rapeseed reduced average daily feed intake (ADFI) compared to the control group (P = 0.002), and egg-laying rate of XH3 rapeseed was lower than that of DY6 rapeseed (P = 0.006), and egg weight of MB1, DY5, and XH3 rapeseed were lower than that of the control group (P = 0.007). Egg mass was reduced by 11.5% rapeseed and egg mass of XH3 and DY5 rapeseed were lower than that of DY6 rapeseed (P = 0.004). Feed conversion ratio (FCR) of 11.5% rapeseed was higher than that the control group and FCR was higher in XH3 rapeseed than in DY6 rapeseed from 1 to 8 wk (P = 0.008). At wk 8, the lightness value of eggshell color of XH3 rapeseed was significantly lower than that of the control and DY5 rapeseed (P = 0.012). Xiheyou no. 3 rapeseed had a higher redness value of eggshell color than the control and MB1 and DY5 rapeseed (P = 0.008). Albumen height of DY5 rapeseed was lower than that of the control group at wk 8 (P = 0.012). Mianbangyou no. 1 and DY5 rapeseed decreased Haugh unit at wk 4 and 8, respectively (P = 0.011, P = 0.024). Serum estradiol (E2) content was decreased by 11.5% rapeseed (P = 0.003). Thyroid index increased as the Gls and EA content increased (P = 0.008). The smallest hierarchical follicle numbers of XH3 and MB1 rapeseed were lower than that of the control group (P = 0.009). After 4 wk withdrawal, the egg weight, egg mass, and FCR did not recover (P = 0.011, P = 0.033, P = 0.024, respectively). In conclusion, 11.5% rapeseed decreased egg production performance which might be caused by decreasing hormone levels, and high Gls and EA rapeseed had a lower performance than low Gls and EA rapeseed.